Screen baffle for hydraulic sand classifiers



y 26, 1966 F. A. LILLIG ETAL 3,262,550

SCREEN BAFFLE FOR HYDRAULIC SAND CLASSIFIERS 2 Sheets-Sheet l i'iied Sept. 6, 1962 0 r mg M NA e W4 w m 4 4W m f. m L

y 1966 F. A. LILLIG ETAL 3,262,560

SCREEN BAFFLE FOR HYDRAULIC SAND CLASSIFIERS Filed Sept. 6, 1962 2 Sheets-Sheet 2 INVENTOR. R070 4 L//G BY ,q/vo a z/ 064 60 United States Patent O 3,262,560 SCREEN RAFFLE FOR HYDRAULIC SAND CLASSIFIERS Floyd A. Lillig and Andrew Dergo, Cedar Rapids, Iowa, assignors to Iowa Manufacturing Company, Cedar Rapids, Iowa Filed Sept. 6, 1962, Ser. No. 221,730 4 Claims. (Cl. 209-17) The present invention relates to classifying sand and particularly to an improvement in water scalping-classifying tanks therefor of the surface current type.

The art of sand classifying exploits the fact that the falling rates in water of larger grains of said are greater than those of smaller grains. Many devices therefor are in use and well-known, the present invention being particularly directed to the type of classifying apparatus which employs an elongated settling tank and operates by means of an incoming surface current of water and sand to be classified. Such tanks are described generally in US. Patent No. 2,760,634, for instance, and may also incorporate one or more rising current classifiers, as shown, for instance, in US. Patent 2,410,637, toward their upstream end, in order to achieve better classification between the coarse grains. In practice, utilizing this sort of tank, it has been found in cases where the coarse fractions of the incoming sand include many flat grains that the latter tend to plane along in the surface current of the water and thus be carried down the tank to settle with the smaller classification instead of settling upstream as they should with the other coarser but more cubical-shaped grains. Depending, of course, on the prevalence of the flat grains, such planing can seriously upset the classifying ability of the tank and result in a deficiency of coarse classification and a corresponding poor classification among the fines. Prevention of such erratic operation of the tank when flat grains are encountered is the chief object of the present invention.

.When the number of flat coarse grains are substantial enough to upset the operation of the tank, the present invention inserts a screen baflle in the tank to intercept such grains and deflect them down into the tank. The baflle is sized to permit the smaller sizes to pass therethrough and, while it may be placed downstream of the portions of the tank devoted to all the coarse classifications, it is preferably placed just downstream of that portion of the tank or of the inlet of the rising current classifier, as the case may be, associated with the coarsest grains and inclined to deflect the flat grains downwards.

Accordingly, the primary object of the present invention is the provision of a screen bafile in water scalpingclassifying tanks of the kind described to intercept the flat coarse grains in order to prevent their settling out of place in the tank.

Another object of the present invention is to provide tanks of the kind described with an inclined screen baffie just downstream of those portions of the tank associated with the coarser classifications, which bafile is sized to permit only the smaller classifications to pass therethrough.

A further object of the present invention is the provision of a screen baffle downstream of the portion of tanks of the kind described associated with the coarsest classification to deflect downwards into the tank such grains as may have a fiat shape and to pass therethrough all smaller classifications.

Other and further objects, features and advantages of the present invention will be apparent from the preferred forms thereof, hereinafter described, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a truncated side elevational view, partly in section, of a typical water scalping-classifying tank of the surface current type;

FIGURE 2 is a vertical section along the line 2-2 of FIGURE 1;

FIGURE 3 is a truncated side elevational view partly in section of a tank similar to that of FIGURE 1 but with the addition thereto of several rising current classifiers; and

FIGURE 4 is a vertical section along the line 4-4 of FIGURE 3.

With regard now to the drawings, 10 generally represents a typical surface classifying tank having end walls 11 and 12, downwardly converging lower and parallel upper side walls 13, 13 and 14, 14', respectively, and bottom wall 15. A feed box 16 is appropriately mounted on end wall 11 to receive the entering water and sand to be classified, which box in turn communicates with tank 10 through inlet 17 in Wall 11 suitably positioned below the operating water level of tank 10 represented by line A-B. The upper periphery of the downstream one-half or so of tank 10 forms a weir over which the water water flows and is provided with an overflow trough or launder 18 thereabout which discharges through fiume pipe 19. Bottom wall 15 is provided with a series of conventional bleeder valves 20, one of which is shown, spaced appropriately from each other and between end walls 11 and 12 longitudinally of tank 10 according to the classifications desired of the sand entering feed box 16. Each bleeder valve is operated by suitable electric or hydraulic mechanism generally indicated at 21 mounted on beams 22 spanning side walls 14, 14' and by vertical operating rods 23. Operating mechanisms 21 are controlled by paddle wheels 24 rotated by vertical shafts 25. When the classified sand associated with one of the bleeder valves reaches a depth sufficient to restrict the revolution of the paddle wheel 24 associated with that valve, the latter is opened by its operating mechanism 21 and rod 23 and closed thereby when paddle wheel 24 begins to revolve again upon the lowering of the level of the classified sand thereabout. Each bleeder valve in turn communicates through bottom wall 15 with a splitter 26 provided with one or more laterally adjacent metering gates 27 (one only being shown for each splitter in FIG- URES l and 3) emptying into fiume 28 having one or more laterally adjacent cellsaccording to the number of gates 27 at each splitter 26. Inasmuch as the construction and operation of water scalping-classifying tanks of this type are well known no further description of tank 10 is deemed necessary.

Owing to the velocity and quantity of sand and water entering tank 10 through inlet 17, any flat grains, especially of the coarser size, tend to plane along in the surface current of water and sand moving downstream of tank 10 so as not to settle where they should in the upstream portions thereof. To intercept these flat grains, a screen bafile 30 is removeably fixed by any appropriate means in tank 10 between side walls 13, 13' and 14, 14. Radio 30 extends both above Water level A-B and below the level of inlet 17 with its upper end being inclined toward upstream end wall 11 in order to deflect the intercepted grains downwardly into tank 10. Usually one such bafiie is sufiicient and in that case is preferably placed just downstream of the portion of tank 10 devoted to the coarsest grains (see FIGURE 1). The screen may be either of slotted (as shown) or square mesh and is sized to permit all but the coarsest classification to pass therethrough. If desired or necessary, however, bafile 30 may be located in the same manner just downstream of all the several portions of tank devoted to the coarse classifications with, of course, an appropriate reduction in mesh size. Or, indeed, several such bafiles may be used, one for each coarse classification, the mesh size of each being appropriate for the classifications it must reject and pass.

In the alternate form shown in FIGURES 3 and 4, the structure is the same as that in FIGURES l and 2, identical reference numerals being employed, except that tank 10 is provided with several rising current classifiers along the bottom portion thereof for the coarse classifications. The classifiers are formed simply by means of a series of partitions 40 transversely of tank 10 and spaced from each other and from end wall 11 to form a sequence of compartments 41. The latter are provided with a common top wall 42 in which, in turn, are slotted orifices 43 communicating with each compartment 41. Orifices 43 extend transversely with respect to tank 10 and each is made adjustable by means of a lip 44 slideable on top wall 42 longitudinally of tank 10 to narrow or widen each orifice as may be required. A water inlet pipe 45 communicates with each compartment 41 to supply the rising current therefor. Since the design and operation of rising current classifiers is well known no further description of their structure or operation is necessary.

In order to deal with the fiat coarse grains incoming through inlet 17, a screen bafile 50 is removably fixed by appropriate means so that it extends transversely of tank 10 from the downstream edge of one orifice 43, preferably that of the classifier associated with the coarsest classification, to above the water level A-B of tank 1% (see FIGURES 3 and 4). The mesh of baffle 50 is sized in the same manner as that of halide 3t) and bafile 50 may be alternately positioned, or a baffie provided for each classifier, in the manner described in connection with ibafile 30 in the embodiment of FIGURES l and 2.

Though the invention has been described in particular terms and embodiments, it is not so limited, and the following claims are to be read as encompassing such variations and modifications as would occur to one working in the art to which the invention relates.

We claim:

1. In a sand classifier including an elongated water scalping tank having side and bottom walls and inlet and outlet end walls, an inlet in the upper portion of said inlet end wall for water and sand to be classified, said sand and water passing from said inlet toward said outlet end wall at a rate and level efiective to cause the coarsest classification-of the sand to be deposited on said bottom wall adjacent said inlet end wall and progressively finer classifications of the sand to be deposited on said bottom wall at locations progressively further from said inlet end wall toward said outlet end wall, rising current classifiers in said tank comprising a plurality of adjacent compartments in the lower portion of said tank located beginning adjacent said inlet end wall and extending sequentially part way toward said outlet end wall, each of said compartments enclosing the location on said bottom wall of the deposit of one of the coarse classifications of the sand, each of said compartments including a top wall below the level of said inlet provided with an adjustable orifice therein extending transversely of said tank and a water inlet thereto effective to provide a flow of water from said compartment up through said orifice, and a plurality of valves in said bottom wall for withdrawing each classification of the sand therefrom, the combination therewith of a stationary screen bafile extending transversely of said tank between its side walls and positioned just downstream of one of said orifices in said top walls, said baffle being of such screen size and extending from the top wall of said compartment to above the operating water level in said tank elfective to prevent passage through said baflle of at least one of said coarse classifications while permitting passage therethrough of the finer classifications.

2. In a sand classifier including an elongated water scalping tank having side and bottom walls and inlet and outlet end walls, an inlet in the upper portion of said inlet end wall for water and sand to be classified, said sand and water passing from said inlet toward said outlet end wall at a rate and level effective to cause the coarsest classification of the sand to be deposited on said bottom wall adjacent said inlet end wall and progressively finer classifications of the sand to be deposited on said bottom wall at locations progressively further from said inlet end wall toward said outlet end wall, rising current classifiers in said tank comprising a plurality of adjacent compartments in the lower portion of said tank located beginning adjacent said inlet end wall and extending sequentially part way toward said outlet end wall, each of said compartments enclosing the location on said bottom wall of the deposit of one of the course classifications of the sand, each of said compartments including a top wall below the level of said inlet provided with an adjustable orifice therein extending transversely of said tank and a water inlet thereto effective to provide a flow of water from said compartment up through said orifice, and a plurality of bleeder valves in said bottom wall for withdrawing each classification of the sand therefrom, the combination therewith of a stationary screen baffle extending transversely of said tank between its side walls and positioned just downstream of said orifice of the one of said compartments associated with the coarsest classification of the sand, said bafile being of such screen size and extending from the top wall of said compartment to above the operating water level in said tank so that passage through said ballie of said coarsest classification is prevented while passage therethrough of the finer classification is permitted, the top of said bafiie being inclined with respect to said water level toward said inlet effective to deflect said coarsest classification striking said baflle downwards into said tank.

3. In a sand classifier including an elongated water scalping tank having side and bottom walls and inlet and outlet end walls, an inlet in the upper portion of said inlet end wall for water and sand to be classified, said sand and water passing from said inlet toward said outlet end wall at a rate and level effective to cause the coarsest classification of the sand to be deposited on said bottom wall adjacent said inlet end wall and the less coarse classifications of the sand to be deposited on said bottom wall at locations progressively further from said inlet end wall toward said outlet end wall, and a plurality of means in said bottom wall spaced between said end walls and from each other longitudinally of said tank for withdrawing each coarse classification of the sand therefrom, the combination therewith of a stationary screen bafile extending transversely of said tank between its side walls and positioned just downstream of said with drawing means for one of said coarse classifications, said bafile being of such screen size and extending above the operating water level in said tank and below the level of said inlet thereto effective to prevent passage through said battle of said one of said coarse classifications while permitting passage therethrough of the less coarse classifications.

4. In a sand classifier including an elongated water scalping tank having side and bottom walls and inlet and outlet end walls, an inlet in the upper portion of said inlet end wall for water and sand to be classified, said sand and water passing from said inlet toward said outlet end wall at a rate and level effective to cause the coarsest classification of the sand to be deposited on said bottom wall adjacent said inlet end wall and the less coarse classifications of the sand to be deposited on said bottom wall at locations progressively further from said inlet end wall toward said outlet end wall, and a plurality of means in said bottom wall spaced between said end walls and from each other longitudinally of said tank for withdrawing each coarse classification of the sand therefrom, the combination therewith of a stationary screen baflle extending transversely of said tank between its side walls and positioned just downstream of the one of said withdrawing means for the coarsest classification of the sand, said baifie being of such screen size and extending above the operating water level in said tank and :below the level of said inlet thereto so that passage through said bafiie of said coarsest classification is prevented while the passage therethroagh of the less coarse classifications is permitted, the top of said baffle being inclined with respect to said water level toward said inlet efiective to deflect said coarsest classification striking said baflle downwards into said tank.

References Cited by the Examiner UNITED STATES PATENTS Stanley 209-157 OBoyle et al. 209158 Darby 209-454 Saxe 209-208 Sherman et a1. 251145 Hukki 209-17 Examiners.

S. WILLIAMS, Assistant Examiner. 

3. IN A SAND CLASSIFIER INCLUDING AN ELONGATED WATER SCALPING TANK HAVING SIDE AND BOTTOM WALLS AND INLET AND OUTLET END WALLS, AN INLET IN THE UPPER PORTION OF SAID INLET END WALL FOR WATER AND AND TO BE CLASSIFIED, SAID SAND AND WATER PASSING FROM SAID INLET TOWARD SAID OUTLET END WALL AT A RATE AND LEVEL EFFECTIVE TO CAUSE THE COARSEST CLASSIFICATION OF THE SAND TO BE DEPOSITED ON SAID BOTTOM WALL ADJACENT SAID INLET END WALL AND THE LESS COARSE CLASSIFICATION OF THE SAND TO BE DEPOSITED ON SAID BOTTOM WALL AT LOCATIONS PROGRESSIVELY FURTHER FROM SAID INLET END WALL TOWARD SAID OUTLET END WALL, AND A PLURALITY OF MEANS IN SAID BOTTOM WALL SPACED BETWEEN SAID END WALL AND FROM EACH OTHER LONGITUDINALLY OF SAID TANK FOR WITHDRAWING EACH COARSE CLASSIFICATION OF THE SAND THEREFROM, THE COMBINATION THEREWITH OF A STATIONARY SCREEN BAFFLE EXTENDING TRANSVERSELY OF SAID TANK BETWEEN ITS SIDE WALLS AND POSITIONED JUST DOWNSTREAM OF SAID WITH DRAWING MEANS FOR ONE OF SAID COARSE CLASSIFICATIONS, SAID BAFFLE BEING OF SUCH SCREEN SIZE AND EXTENDING ABOVE THE OPERATING WATER LEVEL IN SAID TANK AND BELOW THE LEVEL OF SAID INLET THERETO EFFECTIVE TO PREVENT PASSAGE THROUGH SAID BAFFLE OF SAID ONE OF SAID COARSE CLASSIFICATIONS WHILE PERMITTING PASSAGE THERETHROUGH OF THE LESS COARSE CLASSIFICATIONS. 